KR20170100262A - Method for manufacturing tube members of high strength copper alloys - Google Patents

Abstract

The present invention relates to a method of manufacturing a tube member using copper alloy and, more specifically, relates to a method of manufacturing a tube member of a high strength copper alloy capable of significantly reduce a number of processing when compared to a conventional cold working method without using a cutting process. According to the present invention, the method of manufacturing the tube member of the high strength copper alloy comprises: a step of cold companding a base tube manufactured by a high strength copper alloy; a step of annealing the cold companded tube material; a step of applying a lubricant to a surface of the annealed tube material; and a step of drawing the tube material applied with the lubricant.

Description

TECHNICAL FIELD [0001] The present invention relates to a method of manufacturing a high strength copper alloy tubular member,

The present invention relates to a method of manufacturing a tubular member using a copper alloy, and it is an object of the present invention to provide a method of manufacturing a tubular member using a copper alloy, .

Among the standards of KS D 5101 [copper and copper alloy rods], 6/4 brass is used as a base, and 6/4 brass components are replaced with elements such as Mn, Ni, Al, Sn, Si , The so-called 'C6782' and 'C6783', are the alloys, also called 'Manganese Bronze', which exhibit the best tensile strength and corrosion resistance among the 6/4 brass alloys.

This alloy has been used since it was secondarily processed by casting, hot forging and hot rolled rod-shaped members through drawing process, and its main applications are ship propeller and machine tool valve for mining.

In recent years, there is an increasing demand for the use of excellent corrosion resistance and mechanical properties characteristic of this material for automotive parts.

Most of the automobile parts are formed in the form of a tube. Since the copper alloy material is a rod rather than a pipe, it is necessary to process the rod-like member into a tubular member in order to process it into an automobile part .

On the other hand, in the case of manufacturing a tubular member using a copper alloy having excellent elongation as disclosed in the following patent documents, a tubular member can be manufactured through extrusion to manufacture a tubular body, followed by tube drawing.

However, the copper alloy material has a tensile strength of 450 to 500 MPa, which is higher than that of a general copper alloy and has an elongation of about 15 to 20%, which is smaller than a general copper alloy. Cold Tear is apt to occur when cold working is performed for processing with a tubular member having a reduced diameter of less than 15% (preferably 10% or less) The number of times of drawing and the number of annealing in parallel therewith is increased, and it is practically difficult to process for automobile parts.

Therefore, as shown in FIG. 1, the automotive tubular member made of the alloy can be manufactured by purchasing a bar-shaped member having a predetermined size, cutting it according to the dimensions, performing drilling, And the surface roughness and the dimensional accuracy required by the method.

As described above, the machining of the tubular member of the alloy using the cutting process can meet the quality standards required in the automobile industry, but the machining cost is high, the machining length is limited, , And low productivity.

Korean Patent Publication No. 2009-0087005

The object of the present invention is to provide a high strength copper alloy material which has high tensile strength and low elongation so that it can not be easily processed through cold plastic working to a tubular member having dimensional accuracy and surface roughness required by the automobile industry through cold plastic working And a method for manufacturing the same.

According to an aspect of the present invention, there is provided a method of manufacturing a high-strength copper alloy, comprising the steps of: cold pilging a core pipe made of a high-strength copper alloy; annealing the cold-rolled pipe material; And a step of drawing the tubular member coated with the lubricant. The present invention also provides a method of manufacturing a high strength copper alloy tubular member.

According to the present invention, the dimensional precision and surface roughness required in the automobile industry can be realized by only cold plastic working, and the dimensional accuracy and surface roughness are superior to those of the conventional machining method.

In addition, although the machining method is not suitable for a production method of a long pipe having a low machining accuracy and rough surface due to shaking of a cutting tool when machining a length of 3 to 5 times or more the inner diameter of the inner diameter, Tube), it can be processed in various lengths (several tens of meters or less) for parts required in all industries including the automobile industry.

In addition, the machining process causes considerable loss of material in the course of drilling and reaming, but according to the method of the present invention, such material loss hardly occurs.

In addition, the number of cold working processes can be significantly reduced compared to the simple drawing process, which can greatly reduce the production cost.

FIG. 1 is a manufacturing process diagram of a conventional C6782 high-strength brass tubular member.
2 is a manufacturing process diagram of a C6782 high-strength brass tubular member according to a preferred embodiment of the present invention.
3 is a schematic view for explaining the cold pressing process.
4 is a schematic view for explaining the drawing process.

The singular forms used to describe the embodiments of the present invention are meant to include plural forms unless the phrases expressly mean the opposite. And includes meaning of specific characteristics, regions, integers, steps, and actions. Elements and / or components, and other particular features, regions, integers, steps, acts. Quot; does not exclude the presence or addition of elements, elements and / or groups.

Although not defined differently, all terms including technical terms and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. Also, commonly used predefined terms are not to be construed as ideal or very formal meanings unless further defined and interpreted as having a meaning consistent with the relevant technical literature and the present disclosure.

The inventors of the present invention have studied to realize high dimensional accuracy and surface roughness while reducing processing cost in processing a high strength copper alloy such as C6782 or C6783 of KS D 5101 into a tubular member. As a result, It is possible to increase the cross-sectional reduction rate of the high-strength copper alloy to 50 to 70% even at a low process step, and to achieve excellent dimensional accuracy and surface roughness when the finish machining is subsequently performed by the cold drawing method, The manufacturing cost can be remarkably reduced as compared with the method according to the present invention.

A method of manufacturing a tubular member of a high strength copper alloy according to the present invention includes the steps of cold pressing a core tube made of a high strength copper alloy, annealing the cold-rolled tube member, applying a lubricant to the surface of the annealed tube member And drawing out the pipe material coated with the lubricant.

The capillary tube can be manufactured by various methods such as extrusion, plate working, and welding, and there is no particular limitation on the production method thereof.

The cold pressing may be performed so that the cross-sectional reduction rate of the capillary is 50 to 70%, and the cross-sectional reduction rate is preferably realized through 3 or less, more preferably 2 or less, cold pressing processes. At this time, the annealing process can be performed in the middle in repeating the cold pressing process after cold pressing.

The drawing is a plug drawing process and can be performed so that the sectional reduction ratio is 15 to 25%. The drawing process is preferably performed twice or less, more preferably, one time.

It is preferable to apply a lubricant containing polytetrafluoroethylene (PTFE) to the pipe before performing the drawing process, and the lubricant containing PTFE is required not only to increase the reduction rate of the cross section of the drawing process but also to improve the surface roughness .

The cold rolling and drawing process is preferably performed at 580 to 650 ° C for 20 minutes to 2 hours. If the temperature falls outside the lower limit of the temperature range and time, sufficient annealing is not performed, which adversely affects the next processing. If the temperature and time range are out of the upper limit, the energy cost becomes excessive.

The manufacturing method of the tubular member according to the present invention is not limited to the composition of the copper alloy, but it is particularly preferable that the composition of Cu is 55 to 60.5 mass%, Pb is 0.5 mass% or less, Fe is 0.1 to 1.5 mass%, Al is 0.2 to 2.0 mass %, Mn: 0.5 to 3.0% by mass, and the high-strength copper alloy containing the remaining Zn and unavoidable impurities.

[Example]

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a manufacturing process diagram of a copper alloy tubular member according to a preferred embodiment of the present invention. As shown in Fig. 2, the manufacturing process of the high strength copper alloy tubular member according to the preferred embodiment of the present invention comprises cold pressing the extrusion cap made of C6782 alloy, annealing after cold pressing, A step of coating a lubricant on the pipe material, and a step of pulling out a pipe material on which the lubricant is coated.

First, as the extrusion capillary, a rod having a hollow prepared by melting and casting a C6782 alloy, and extruding and piercing the cast material, the dimensions of which were 68 mm in outer diameter, 6 mm in thickness, and 1000 mm in length.

As shown in Fig. 3, the cold pressurization process comprises a pair of rolls having a tapered concave groove gradually reduced in diameter in the circumferential direction, a pair of rolls arranged in an upward and downward direction, a diameter gradually decreasing in the lengthwise direction, A mandrel that is disposed in the tapered shape and supports the capillary tube, and a discharge tube that supports and discharges the tube that is compressed by the pair of rolls.

In the cold pressing process, the rolls are compressed and compressed to a required thickness and diameter by rotating the capillary tube before and after compression, and the pair of rolls are rotated and retreated several times in accordance with the taper of the mandrel while rotating , And a corrugated tube introduced between the concave grooves of the roll and the mandrel is rolled to produce a tube having a predetermined tube thickness and inner and outer diameters.

Specifically, the reduction ratio of the cross section of the capillary is processed to about 50 to 70% through two cold pressing processes.

In the first cold pressing process, the process is performed so that the outer diameter is 48.2 mm and the thickness is 4.0 mm. The oil attached to the cap is removed through the process of washing the cap before the cold pressing process, and then the cold pressing process is performed.

Specifically, a circular rotary die having two variable dimensional grooves is provided above and below the capillary, and is rotated by 360 degrees, and the die is driven by the bag and pinion gear attached to the coaxial shaft. As a result, no slip occurs between the material and the circular dies, and the mandrel maintains a curved gradient.

Subsequently, in order to remove oil and other impurities adhering to the primary cold-rolled pipe, an organic solvent was used for cleaning, and the pipe was heated to 550 to 650 ° C. and maintained for 30 minutes. The annealing process is performed on the microstructure of the work-hardened tube, and the roundness and straightness are checked.

Then, secondary cold-rolled steel sheets are subjected to a cold-rolled steel pipe having an outer diameter of 25.4 mm and a thickness of 3.0 mm.

In order to secure dimensional accuracy and maintain uniformity of surface roughness and maintain thin thickness, a 3-roll peeler mill is used instead of a 2-roll peeler for primary cold pressing. In the embodiment of the present invention, the last cold pressing is a three-roll structure rolling mill, but the present invention is not limited thereto. In consideration of the thickness of the rolled pipe, a two-roll structure or a three-roll structure may be used .

In order to remove oil and other impurities adhered to the first cold-rolled pipe, the second cold-rolled pipe was subjected to a cleaning work using an organic solvent, heated to 550 to 650 ° C. and held for 30 minutes Annealing is performed on the microstructure of the workpiece cured in the second cold pressing process, and roundness and straightness are checked.

In this way, it is possible to process more than 50% of the section reduction ratio of the tube made of C6782 alloy, which is a high strength copper alloy, through cold pressing twice. In the case of the conventional drawing process, .

A coating containing polytetrafluoroethylene (PTFE) is applied to the surface of the annealed tube. PTFE, which is an organic polymer having an appearance of white, is a solid lubricant which has a smooth and cohesive molecular structure and molecular chains are easily slidable with each other to exhibit a low friction coefficient. A separate medium may be used to enhance the applicability of PTFE.

Then, as shown in Fig. 4, the plug drawing process is performed by placing a plug inside the die and the pipe, pulling the end of the pipe into the chuck, And the plug is processed to have the same shape as the die cavity in the process of passing the material through the space formed between the plug and the plug. This makes it possible to obtain a product having good dimensional accuracy and smooth surface, Accordingly, physical properties such as mechanical properties and workability can be improved. When the plug is pulled out by using the plug, the diameters of the inner and outer surfaces of the tube are controlled well, so that the plug pulling is performed in the embodiment of the present invention.

Meanwhile, in the practice of the present invention, drawing is performed in one step, but the number of drawing can be performed a plurality of times in accordance with the finally required dimensions.

In case of using general lubricant, it is difficult to exceed 10% in cross-section reduction rate at the time of plug drawing, but it is very effective to reduce the number of pull-out because PTFE application can increase cross-sectional reduction rate by more than 20%.

In the embodiment of the present invention, drawing was performed using a drawing machine so as to have an outer diameter of 10.5 mm and a thickness of 2.75 mm. In this case, oil was used as a lubricating method.

The outer diameter tolerance of the finally processed tubular member was within 0.1 mm, and the outer diameter tolerance of the wall thickness was 0.05 mm, and the dimensional accuracy was excellent.

After completion of the drawing process, the organic solvent is used to perform a washing process to remove the adhered oil during the drawing process.

Finally, heat treatment is performed at 600 to 650 ° C for about 15 minutes through a normal tube annealing furnace to control the mechanical properties such as abrasion resistance, strength, and heat resistance of the drawn tubular member.

Claims (7)

A step of cold-pressing a cap made of a high-strength copper alloy;
Annealing the cold drawn steel tube;
Applying a lubricant to the surface of the annealed tubing; And
And drawing out the pipe material to which the lubricant is applied
A method of manufacturing a tubular member of high strength copper alloy. The method according to claim 1,
Wherein the step of cold pressing is such that the reduction ratio of the cross section is 50 to 70%. 3. The method according to claim 1 or 2,
Wherein the step of drawing is performed by a plug drawing process so that the reduction ratio of the cross-sectional area is 15 to 25%. 3. The method according to claim 1 or 2,
Wherein said lubricant comprises PTFE. ≪ RTI ID = 0.0 > 11. < / RTI > 3. The method according to claim 1 or 2,
Wherein the annealing is performed at 550 to 650 占 폚. 3. The method according to claim 1 or 2,
The high-strength copper alloy contains 55 to 60.5 mass% of Cu, 0.5 mass% or less of Pb, 0.1 to 1.5 mass% of Fe, 0.2 to 2.0 mass% of Al, 0.5 to 3.0 mass% of Mn, Wherein the step of forming the tubular member comprises the steps of: 3. The method according to claim 1 or 2,
Wherein the cold-pressing step is performed twice or less.

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